Elevator system

ABSTRACT

An elevator system including an elevator car mounted for movement in the hoistway of a building. Guide elements carried by the elevator car coact with guide rails in the hoistway to guide the elevator car during its movement. Each guide element includes first, second and third interchangeable guide roller assemblies for the face and two opposed guide surfaces, respectively, of a guide rail. Each guide roller assembly is adjustable for coacting with different sizes of guide rails, pivotable to accommodate discontinuities and steps between adjacent guide rails, and flexibly preloaded against its associated guide surface to continuously maintain contact with the guide rail throughout the journey of the elevator car through the hoistway, notwithstanding bowing or misalignment of the guide surfaces.

United States Patent 1191,

Solymos l 3,856,117 [451 Dec. 24, 1974 ELEVATOR SYSTEM v Inventor: Frederick Solymos, Glen Ridge, NJ.

Assignee:

. Pittsburgh, Pa.

Filedz Sept. 25, 1973 Appl. No.: 400,599

US. Cl. 187/95, 308/6 R Int. Cl B66b 7/04 Field of Search 1'87/95, l; 308/3 B, 6 R;

References Cited UNITED STATES PATENTS 2,251,963 2,260,922 Spiro 187/95 Primary Examiner-James B. Marbert Assistant Examiner-James L. Rowland A' Attorney, Agent, 0r Firm D. R. Lackey Westinghouse Electric Corporation,

Spiro ..1s7/9-s ABSTRACT An elevator system including an elevator car mounted for movement in the hoistway of a building. Guide elements carried by the elevator car coact with guide rails in the hoistway to guide the elevator car during I its movement. Each guide element includes first, second and third interchangeable guide roller assemblies for the face and two opposed guide surfaces, respectively, of 'a guide rail. Each guide roller assembly is adjustable for coacting with different sizes of guide rails, pivotable to accommodate discontinuities and steps between adjacent guide rails, and flexibly preloaded against its associated guide surface to continuously maintain contact with the guide rail throughout the journey of the elevator car through the hoistway, notwithstanding bowing or misalignment of the guide surfaces.

12 Claims, 4 Drawing Figures PATENTEnuzc-zmn 3856.117

sumzura ioa , 1 ELEVATOR SYSTEM BACKGROUNDOF THE IN E TION 1. Field of the Invention The invention relates in general to elevator systems, and more specifically to guide elements carried by the elevator car and its counterweight which coact with guide rails to quide the elevator car and counterweight throughout their travel paths.

2. Description of the Prior Art The movable elements of an elevatorv system, such as the elevator car and its counterweight, are guided throughout their respective travel paths in the hoistway of a building. The guiding system conventionally includes guide rails, which have a substantially T-shaped cross-sectional configuration, which rails are fixed in the hoistway, and guide elements, such as guide roller assemblies, with the guide elements being carried by the elevator car and counterweight, The guide ele- Y ments coact with three guide surfaces on the guide rails to guide the movable elements.

When an elevator system is installed, extreme care is taken to-properly align the sections which make up each complete guide rail, and care is'take'n to accurately space the two guide rails which cooperate to guide a'movable element. It is not economically practical, however, to obtain perfectly straight guide rail sections or to install and maintain them in perfect alignment and spacing. Bowing and twisting of one or more of the rail sections, and misalignmentof adjacent rail sections,'cause horizontal movement or sway of the elevator car, degrading ride quality. Ride quality has been improved, notwithstanding rail misalignment and discontinuities, by roller guide assemblies constructed to accommodate misalignment and discontinuities, and to cushion their affect on the elevator car.- Guide rollers have been preloaded againstthe guide surface of the guide rail, to thus follow the rail guiding surface despite bowing or tw-isting thereof, and they have been pivotally mounted to enable the guide rollers to accommodate discontinuities'and steps between guide rail sections without transmitting objectionable bumps or other undesirable side motions to the elevator car.

The conventional T-shaped guide rail defines three guide surfaces, one on the nose or face of the stem por-' tion, and one on each side of the opposed surfaces of the stern. Thus, each guide element includes three guide roller subassemblies for coacting with these three surfaces.

Guide rails are available in a plurality of different weights and dimensions, with the size of the rail being dictated by the specific application thereof. Differenttion of the preload feature,'and may preload the other subassemblies without the pivot function, resulting in guide roller subassemblies which. are different and not interchangeable between all of the threeguide positions. Further, adjustment is not available to the extent that different sizes of guide rails may be accommodated by a single guide element.

Briefly, the present invention is a new and improved elevator system which includes an elevator car mounted for movement in the hoistway of a building. The elevator car and counterweight, if used, are guided in the hoistway by T-section guide rails fastened to the walls of the hoistway, and by guide elements carried by the car and counterweight which coact with the guide surfaces of the guide rails. Each guide element includes three guide roller subassemblies of like construction which are interchangeable between the three guide positions of the guide element, and which provide preload and pivot functions while being adjustable to accommodate the dimensions of different sizes of guide rails.

The guide roller subassemblies each include a pair of spaced guide rollers joumaled for rotation relative to common support plates, with each subassembly being pivotable about a midpoint thereof, independent of the resilient or flexible preload feature. Size adjustment is provided for each roller subassembly, enabling each roller subassembly to be adjusted to accommodate the specific rail it is coacting with. 25

BRIEF DESCRIPTION OF THE DRAWINGS The invention may be better understood, and further advantages and uses thereof more readily apparent, when considered in view of the following detailed description of exemplary embodiments, taken with the accompanying drawings, in which:

FIG. 1 is a perspective view of an elevator system in cluding an elevator'car and guide arrangement constructed according to the teachings of the invention;

and

FIGS. 2, 3 and 4 are elevational, plan and perspective views, respectively, of a guide element constructed according to the teachings of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawings, and FIG. 1 in particular, there is shown an elevator system 10 constructed according to the teachings of the invention. While the elevator system 10 is illustrated as being of the electric traction type, the invention is applicable to any guided element of an elevator system, including the counterweight, and hydraulic elevator cars.

Elevator system 10 includes an elevator car 12 mounted for movement in a hoistway 14 of a building having a plurality of floors, such as'indicated at 16, which floors are served by the elevator car 12. Hoisting ropes or cables 18 interconnect the elevator car 12 with a counterweight via a traction sheave drive arrangement, which may be conventional and are not shown. The counterweight may be guided according to the teachings of the invention, in the same manner as will be hereinafter described relative to the elevator car i The elevator car 12 is supported by a conventional car frame or sling20 which includes crosshead and safety channel members 22 and 24, respectively, and upright members or stiles 26 and 28.

The elevator car 12 is guided during its movement up and down the hoistway 14 via a guide system which includes guide rails 30 and 32 securely fastened to opposite sides of the hoistway. Guide elements carried by the elevator car 12 coact with the guide rails 30 and 32 to complete the guiding system. Two guide elements 34 and 36 are fastened to the crosshead channel 22, and two guide elements, such as guide element 38, are fastened to the safety channel 24-.

The guide rails 30 and 32 are constructed of a plurality of aligned rail sections, resulting in joints, such as joint 40, at predetermined spaced locations along the rail. An increase in spacing between certain adjacent rail sections creates a discontinuity, and misalignment between adjacent rail sections creates a step, with these discontinuities and steps being felt as bumps in the elevator car. Misalignment, including'bowed and twisted rail sections create car sway whichincreases with car speed. Since it is economically impractical to obtain and maintain perfectly straight railsections, and to perfectly align them and to maintain such alignment, a certain amount of discontinuity and misalignment is tolerated as the adverse affect on ride quality can be substantially reduced through proper design of the guide elements. Guide elements have been designed in which certain of their guide roller subassemblies are preloaded against their associated guide surfaces to thus enable the guide rollers to follow the guide surface despite the surface wandering from the ideal or perfect location. Guide elements have also been, designed in which certain of the guide roller subassemblies of the guide element are pivotally mounted to accommodate discontinuities'and steps between adjacent rail sections without transmitting an objectionable bump into the car. However, the overall construction and design of a guide element usually prohibits incorporating both features into each of the three guide roller subassemblies. Further, the guide roller subassemblies are usually not interchangeable between any of the three guide positions of the guide element, and the guide roller subas-- semblies,if adjustable at all, are only adjustable to the extent necessary to accommodate a single size of guide rail.

FIGS. 2, 3 and 4 are elevational, plan and perspective views, respectively, of a new and improved guide element constructed according to the teachings of the invention, which may be used for the guide element shown in FIG. 1. Since each of the four guide elements for guidingelevator car 12,, in cooperation with the guide rails 30 and 32, are of like construction, only one of the elements, such as guide element 34 need be shown and described in detail, and accordingly, the guide element shown in FIGS. 2, 3 and 4 will be referred to as guide element 34.

Guide element 34 includes a supporting structure having a mounting base 42 in which a plurality of openings 44 are disposed for receiving bolts 46 which are used to secure the base of the guide element 34 to the crosshead or safety channel of the elevator car. Two right angle members '48 and 50 are secured in upstanding, spaced relation on mounting base 42, such as by welding, to provide a predetermined space between two parallel surfaces of adjacent leg portions of the angle members 48 and 50. A structure 52 is disposed in the space, which includes a U-shaped portion having outwardly extending leg members 54 and 56 formed of side bars 58 and 60, respectively, which are welded to the facing sides of angle members 48 and 50, and a bight portion 62 formed of a block 63'welded between the side bars 58 and 60. The leg portions 54-and 56 extend outwardly past the angle members 48 and 50 and define a space 79 sized to receive the stem portion 64 4 of the guide rail 30,while providing a predetermined spacing between thezstem of the guide rail 30 and the surfaces which define the space 79. The base member 42 is cut out or recessed at 77 to also receive the stem 64.

Asbest illustrated in FIG. 3, the stem portion 64 of guide rail 30 includes three guide surfaces, including a nose or face guide surface 66 and first and second opposed side guide surfaces 68 and 70, respectively.

The substantially U-shaped portion .of structure 52 includes first, second and third shaft members 72, 74

and 76, respectively, which extend outwardly from the leg portions 54 and 56, and bight 62. The shaft members 72, 74 and 76 are threaded on their outer ends, as indicated at 78, 80 and 82, respectively. The shaft members 74 and 76 extend outwardly in opposite directions from leg portions 54 and 56, in a coaxial spaced relationship, and shaft member 72 extends outwardly from bight 62, opposite the side which cooperates to define the space 79. The longitudinal axis of shaft member 72 lies in a horizontal plane which includes the longitudinal axes of shaft members 74 and 76, and is oriented such that an extension of its longitudinal axis is perpendicular to an imaginary extension of the longitudinal axes of shaft members 74 and 76, within the space 79. It will be noted from FIG. 3 that extensions of the longitudinal axes of shaft members 72, 74 and 76 are perpendicular to the guide surfaces 66, 68 and 70, respectively, of the guide rail 30. The base 42, angles 48 and 50,structure 52, and shaft members 72,74 and 76 complete the supporting portion of the guide element 34.

Guide element 34 includes first, second and third roller subassemblies 90, 92 and 94, respectively, which are mounted on shaft members 72, 74 and 76, respectively, of the support structure. Each of the roller, assemblies 90, 92.and 94 are of like construction, and may be disposed on. any of the shaft members interchangeably. Since each of the roller assemblies are of like construction, only roller assembly 92 will be demay include first and second spaced, elongated plate members and 102, respectively. Plate members 100 and 102 have openings adjacent their outer ends, such as opening 103 adjacent the upper end of plate 100, and an opening at substantially their midpoints. The openings adjacent the outer ends of plate member 100, such as opening 103, are threaded, while the similarly located openings in plate member 102 may be unthreaded. Each guide roller, such as guide roller 98, includes a hub portion 104 journaled for rotation on a shaft member 106, such as by ball or roller bearings. An elastomeric tire 108 is disposed on hub 104, which tire may be formed of any suitable elastomer such as rubber or polyurethane. In like manner, guide roller 96 includes a hub 109 journaled for rotation on a shaft member 111, and an elastomeric tire 113.

Roller assembly 92 alsoincludes a sleeve member 110, which may be a metallic block having major opposed surfaces 112 and 114 and an, opening 116 extending between these surfaces, which opening is sized to snugly but slidably receive the threaded metallic to two of the opposing sides thereof, which sides join the major opposed surfaces 112 and 114. The longitudinal axes of trunnions 118 and 120 are coaxial, with imaginary extensions thereof intersecting the longitudinal axis of opening 116 with a right angle.

Sleeve member 110 also includes a tubular guide member 122 having an opening 124 which is in registry with, but larger than, opening 116. Guide member 122 is secured, such as by welding, to one of the major opposed surfaces of sleeve 110, such as to surface 112. Tubular guide member 122 cooperates with a resilient member 126 to provide a pre-load function, as will be hereinafter explained. Resilient member 126 includes an opening 128 sized to receive shaft member 80, and a diameter which snuglybut slidably cooperates with the inside diameter of opening 124 in guide member 122. Resilient member 126 may be formed of an elastomeric material, such as rubber or polyurethane, as illustrated, or it may be a compression spring.-

Roller assembly 92 is assembled by disposing spacer members overone end of each of the shaft members 106 and 111, such as spacer member 130 shown disposed over an end of shaft member 111, and the ends of the shafts with the spacers thereon are threadably engaged with the threaded openings in plate 100, such as opening103 for shaft 111. Sleeve member 110 is positioned on plate member 100'with its trunnion 118 extending into the central opening disposed in the plate 100. The outside diameter of shaft 118 and the inside diameter of the opening are selected to enable the plate 100 to rotate or pivot about shaft 118. Spacer members are placed over the remaining ends of shaft members 106 and 111, such as spacer member 132 on shaft 111, and plate member 102 is then placed into position, in spaced parallel relation with plate 100, such that the remaining ends of shaft members 111 and 106 extend through the openings adjacent the ends of plate 102, and the shaft member or trunnion 120 extends into the central opening of plate 102. Lock washers 134 and 136 and hex nuts 1.38 and 140 are assembled with shaft members 106 and 111, respectively, to complete the roller assembly 92. The roller guide wheels 96 and 98, along with their common support plates 100 and 102, are free to pivot on tru'nnions 118 and 120 of the sleeve member 110. g

The mounting or support structure of the guide element 34 is fixed in position on the movable element of the elevator system, such as to the sling of the elevator car, or'to the frame of the counterweight, with the stem of the guide rail properly positioned within slot 77 and within the space 79 of the base 42 and structure 52, respectively. Guide roller assembly 92 is then placed into position by telescoping sleeve 110 of the roller assembly 92 over shaft 74 such that guide-122 is on the side of sleeve 110 which is adjacent the. threads 80 of the shaft member 74. The guide roller assembly 92 is advanced inwardly on shaft 74 until the tires 108 and 113 contact guide surface 68 of the guide rail. It will be noted that the roller assembly will automatically ac commodate any guide rail size since it is merely advanced on shaft 74 until it contacts the guide surface.

and advanced into the guide 122, seating on the surface The resilient member 126 is telescoped over shaft 74 112 of sleeve 110-surrounding the opening 116 therein.

' washermember 140 compresses resilient member 126 to provide the desired preload of guide rollers 96 and 98 against guide surface 68. The other nut may then be advanced against the first nut, to firmly maintain the desired pre-load. It will be noted that in addition to the automatic adjustment for rail size, and the preload for maintaining guide contact on bowed or otherwise misaligned rails, that the guide roller assembly 92 is free to pivot about trunnions 118 and 120, to accommodate discontinuities and steps between adjacent rail sections without transmitting undesirable bumps into the associated movable element of the elevator system.

in like manner, guide roller assemblies and 94 are mounted on shaft members 72 and 76, respectively, and guide against guide surfaces 66 and 70, respectively, of the guide rail 30. Guide roller assemblies 90 and 94 are pre-loaded against their respective guide surfaces, and they are each pivotable to accommodate misalignment and discontinuities of the guide surfaces.

in summary, there has been disclosed a new and improved elevator system, and guide arrangement therefor, which inherently and automatically adjusts for the specific size of guide rail, and which will also accom-- ment for bowed or otherwise misaligned rails, as well,

as discontinuities and steps between adjacent rail sections, assures a high grade ride quality with minimum sway and bumps.

I claim as my invention:

1. A roller guide element for coacting with a guide rail to guide the movement of a movable element in a hoistway, comprising:

support means mountable on the movable element adjacent the guide rail, said support means includ ing first, second and third shaft members extending outwardly therefrom, I

first, second and third roller assemblies of like construction mounted on said first, second and third shaft members, respectively,

each of said roller assemblies including a sleeve member, first and second guide rollers journaled for rotation relative to a common support structure, and means pivotally mounting said common support structure on said sleevemember,

said sleeve member defining a first opening for slidably guiding the sleeve member on its associated shaft member, and a communicating second opening of larger diameter adjacent the outwardly extending end of the shaft, providing'a flat surface surrounding the first opening which is substantially perpendicular to the longitudinal axis thereof,

said sleeve member being slidable on its associated shaft member to adjustably accommodate different guide rail dimensions,

and means for adjustably preloading each of said roller assemblies against the guide surface of a guide rail including threads disposed on the outwardly extending end of each shaft member, a bias member disposed about each shaft member which exstops beyond which the sleeve members cannot move.

2. The roller guide element of claim 1 wherein the longitudinal axes of the first, second and third shaft members lie in a common horizontal plane, with the second and third shaft members'being coaxially spaced to enable the guide surfaces of a guide rail to be disposed therebetween, and with the longitudinalaxis of the first shaft member perpendicularly intersecting a continuation of the axes of the second and third shaft members within' the space between the second and third shaft members.

3. The roller guide element of claim 1 wherein the means pivotally mounting the common support structure of the first and second guide rollers on the sleeve member include first and second trunnions fixed to and extending outwardly from the sleeve member.

4. The roller guide element of claim 1 wherein the bias member is constructed of an elastomeric material.

5. The roller guide element of claim 1 wherein the support means includes a substantially U-shaped portion having a bight and first and second leg members defining a slot for receiving guide surfaces of a guide rail, with the first second and third shaft members being mounted on and extending outwardly from, the bight and first and second leg members, respectively.

6. The roller guide element of claim 5 wherein the longitudinal axes of the first, second and third shaft members lie in a common horizontal plane.

7. An elevator system, comprising:

an elevator car mounted for movement in the hoistway of a building,

a guide rail disposed in the hoistway, said guide rail having first, second and third guide surfaces thereon,

a guide element carried by said elevator car which coacts with said guide rail to guide the movement of said elevator car in the hoistway,

said guide element including support means having first, second and third shaft members perpendicularly spaced from the first, second and third guide surfaces, respectively, of said guide rail, and first, second and third roller assemblies of like construction slidably mounted on said first, second and third shaft members, respectively, and adjustably positioned on their respective shaft members to accommodate thedimensions of the guide rail,

which encircles the associated shaft member, and

each of said roller assemblies having a sleeve member first and second guide rollers journaled for rotation relative to a common support structure, and including means pivotally mounting said common support structure on said sleeve member,

said sleeve member defining a first opening for slidably guiding the sleeve member on its associated shaft member, and a communicating second opening of larger diameter adjacent the outwardly extending end of the shaft, providing a flat surface surrounding the first opening which is substantially perpendicular to the longitudinal axis thereof,

and meansadjustably preloading the guide rollers of each of said first, second and third roller assemblies against said first, second and third guide surfaces, respectively, of said guide rail,

said means including threads disposed on the outwardly extending end of each shaft member, a bias member disposed about each shaft member which extends into the second opening of said sleeve member, and means threadably engaged with each shaft member which is advanced on the shaft memher to contact and compress the bias member against the flat surface surrounding the first opening of said sleeve member, said means threadably engaged with each shaft member providing positive stops beyond which the sleeve members cannot move. I

8. The elevator system of claim 7 wherein the longitudinal axes of the first, second and third shaft members lie in a common horizontal plane, with the second and third shaft members being coaxially spaced to enable the guide surfaces of a guide rail to be disposed therebetween, and with the longitudinal axis of the first shaft member perpendicularly intersecting a continuation of the axes of the second and third shaft members within the space between the second and third shaft members.

9. The elevator system of claim 7 wherein the means pivotally mounting the common support structure of the first and second guide rollers on the sleeve member include first and second trunnions fixed .to and extending outwardly from the sleeve member.

10. The elevator system of claim 7 wherein the bias member is constructed of an elastomeric material.

11. The elevator system of claim 7 wherein the support means of the guide element includes a substanbers lie in a common horizontal plane. 

1. A roller guide element for coacting with a guide rail to guide the movement of a movable element in a hoistway, comprising: support means mountable on the movable element adjacent the guide rail, said support means including first, second and third shaft members extending outwardly therefrom, first, second and third roller assemblies of like construction mounted on said first, second and third shaft members, respectively, each of said roller assemblies including a sleeve member, first and second guide rollers journaled for rotation relative to a common support structure, and means pivotally mounting said common support structure on said sleeve member, said sleeve member defining a first opening for slidably guiding the sleeve member on its associated shaft member, and a communicating second opening of larger diameter adjacent the outwardly extending end of the shaft, providing a flat surface surrounding the first opening which is substantially perpendicular to the longitudinal axis thereof, said sleeve member being slidable on its associated shaft member to adjustably accommodate different guide rail dimensions, and means for adjustably preloading each of said roller assemblies against the guide surface of a guide rail including threads disposed on the outwardly extending end of each shaft member, a bias member disposed about each shaft member which extends into the second opening of said sleeve member, and means threadably engaged with each shaft member which is advanced on the shaft member to contact and compress the bias member against the flat surface surrounding the first opening of said sleeve member, said means which is threadably engaged with each shaft member providing positive stops beyond which the sleeve members cannot move.
 2. The roller guide element of claim 1 wherein the longitudinal axes of the first, second and third shaft members lie in a common horizontal plane, with the second and third shaft members being coaxially spaced to enable the guide surfaces of a guide rail to be disposed therebetween, and with the longitudinal axis of the first shaft member perpendicularly intersecting a continuation of the axes of the second and third shaft members within the space between the second and third shaft members.
 3. The roller guide element of claim 1 wherein the means pivotally mounting the common support structure of the first and second guide rollers on the sleeve member include first and second trunnions fixed to and extending outwardly from the sleeve member.
 4. The roller guide element of claim 1 wherein the bias member is constructed of an elastomeric material.
 5. The roller guide element of claim 1 wherein the support means includes a substantially U-shaped portion having a bight and first and second leg members defining a slot for receiving guide surfaces of a guide rail, with the first, second and third shaft members being mounted on and extending outwardly from, the bight and first and second leg members, respectively.
 6. The roller guide element of claim 5 wherein the longitudinal axes of the first, second and third shaft members lie in a common horizontal plane.
 7. An elevator system, comprising: an elevator car mounted for movement in the hoistway of a building, a guide rail disposed in the hoistway, said guide rail having first, second and third guide surfaces thereon, a guide element carried by said elevator car which coacts with said guide rail to guide the movement of said elevator car in the hoistway, said guide element including support means having first, second and third shaft members perpendicularly spaced from the first, second and third guide surfaces, respectively, of said guide rail, and first, second and third roller assemblies of like construction slidably mounted on said first, second and third shaft members, respectively, and adjustably positioned on their rEspective shaft members to accommodate the dimensions of the guide rail, each of said roller assemblies having a sleeve member which encircles the associated shaft member, and first and second guide rollers journaled for rotation relative to a common support structure, and including means pivotally mounting said common support structure on said sleeve member, said sleeve member defining a first opening for slidably guiding the sleeve member on its associated shaft member, and a communicating second opening of larger diameter adjacent the outwardly extending end of the shaft, providing a flat surface surrounding the first opening which is substantially perpendicular to the longitudinal axis thereof, and means adjustably preloading the guide rollers of each of said first, second and third roller assemblies against said first, second and third guide surfaces, respectively, of said guide rail, said means including threads disposed on the outwardly extending end of each shaft member, a bias member disposed about each shaft member which extends into the second opening of said sleeve member, and means threadably engaged with each shaft member which is advanced on the shaft member to contact and compress the bias member against the flat surface surrounding the first opening of said sleeve member, said means threadably engaged with each shaft member providing positive stops beyond which the sleeve members cannot move.
 8. The elevator system of claim 7 wherein the longitudinal axes of the first, second and third shaft members lie in a common horizontal plane, with the second and third shaft members being coaxially spaced to enable the guide surfaces of a guide rail to be disposed therebetween, and with the longitudinal axis of the first shaft member perpendicularly intersecting a continuation of the axes of the second and third shaft members within the space between the second and third shaft members.
 9. The elevator system of claim 7 wherein the means pivotally mounting the common support structure of the first and second guide rollers on the sleeve member include first and second trunnions fixed to and extending outwardly from the sleeve member.
 10. The elevator system of claim 7 wherein the bias member is constructed of an elastomeric material.
 11. The elevator system of claim 7 wherein the support means of the guide element includes a substantially U-shaped portion having a bight and first and second leg members defining a slot for receiving the guide surfaces of the guide rail, with the first, second and third shaft members being mounted on and extending outwardly from the bight and first and second leg members, respectively.
 12. The elevator system of claim 11 wherein the longitudinal axes of the first, second and third shaft members lie in a common horizontal plane. 